One form of cursor controlled user interface system is described in U.S. Pat. No. 4,464,652. In such a system an input device called a "mouse" is employed by an operator (user) to move a cursor (pointer) symbol about a CRT display screen in order to generate control commands. The mouse is provided with a button to allow the operator to generate control commands to signal the selection of option choices and to perform other control functions. Option choices are made by positioning the cursor on various "menus" which are called up and presented on the screen. Individual items within a menu are selected by operating the mouse button when the cursor is positioned on the selected item.
Prior art systems of this type are limited in their capabilities due to several factors. First, a menu bar is present at all times across the top of the display screen to enable the user to call up menus. The continuous presence of the menu bar cuts down on the usable display space. Further, the single mouse button permits only a limited range of selection and control functions to be performed.